The use of a single ramp from the shore to a floating dock below is a typical method of harbor access. This method usually allows some access to the dock at all tides. When the tide is high, the slope of the ramp may be gentle enough to provide access for large loads and disabled people. However, during low tide, as the dock level drops relative to the land, the slope of the ramp may be dangerous for anyone. The problem is amplified in inclement weather and with large tidal variations. In an attempt to deal with this problem, longer ramps have been used thereby reducing the ramp slope change relative to the dock level change. However, a ramp long enough to maintain a gentle slope may be infeasible due to harbor configuration, the difficulty a disabled person may have climbing such a long ramp without places to rest along the way, and the complexity and weight of such a ramp. Thus, harbor access in areas of large water-level variations can be difficult, especially for those using wheelchairs, crutches, or braces, or those carrying loads.
The maximum ideal slope for persons using wheelchairs, crutches, or braces is 4.8 degrees, i.e., 1:12 rise over run, equating to an 8.33% grade. Hence, a tidal variation of 25 feet would require a 300 foot ramp to maintain a 4.8 degree slope. Conventional harbor access ramps may not attain such a gentle slope even at highest tide.
Prior art mooring or harbor access systems designed to maintain a gentle slope with changes in water level must be manually readjusted when the water level changes more than a few feet. One typical system utilizes two interconnected ramps, the first of which extends from shore and is manually adjustable along a pencil anchor. The second ramp is pivotally connected to the first ramp on its landward end while its waterward end rides upon the floating dock. The slope of the first ramp can be manually changed to accommodate a drastic change in water level (i.e., more than a few feet). This prior art system deals with small changes in water level due to waves but cannot adequately deal with constant large changes such as tides. Manual readjustment would be a difficult and infeasible task on a body of water with a constantly and broadly changing level, such as ocean waters.